When, geometrically, do you know you have BI?
 

Standard sizes (high school) all the way around.

Saw this tonight. A1 drives in, puts ball off of the backboard, defender pins ball to backboard, just inside the smaller painted rectangle above the rim.

No call from the officials, but I'm thinking that their has to be a line within that rectangle where if the ball is touching the backboard inside of that boundary that part of the ball has to be over the cylinder.

Is there a rule of thumb for this?

Here is a crappy image showing the rectangle, er, "shooter's square".
http://www.youth-basketball-tips.com...odbankshot.gif

Well if the defender touched the ball after it hit the backboard, is it not goaltending anyways?

Not in high school.
 

It was unclear if the ball was on its downward flight. I don't think it was, but lets say it wasn't.

You have to have 3 things to have Goaltending.

1. Ball must be completely above the rim.
2. Ball must be on its downward flight.
3. Ball must have a chance to go in.

If any of these things are not present, then you do not have a violation.

It is possible that one of these things was not present and the officials passed on the play. The backboard or the ball touching the backboard has nothing to do with this call the high school level. Only at the college level is the backboard a factor.


Peace

I'm talking about Basket Interference.
Part of the basketball may have been in the imaginary cylinder with the basket as its base.
Wanting to know where that area is on the back board.

Recently Andris Biedrinch of the Warriors was called for a violation when he knocked the ball off the flange during live action. In NBA it was goaltending (i think) but would have been basket interference in HS.

If the ball is contacting the backboard directly behind the basket part of the basketball MUST be in the cylinder, given the size of the ball.

At some point further away from the center of the backboard this must also be true. How far out can you go and have an automatic, provable by geometry basket interference?

Rim diameter is 18", Ball diameter is 9". The square in question is 18" tall and 24" wide. So once about 1/4 of the ball is within the square then it has penetrated the imaginary cylinder above the basket. So yes by geometry BI could be called it the ball is contacted after the referee observes that a 1/4 or more of the ball is inside the square.

The backboard has nothing to do with that. There is not point on the back board that has anything to do with this kind of call. And the ball must be on the cylinder to have BI if you are not touching the ball. And if you are touching the ball, the ball must be above the cylinder.


I do not know all NBA terminology, but I bet that they consider similar things as BI. I do think they cannot hit the backboard, but that is something I am not sure about. I doubt what you described is GTing.

I think you are honestly trying to figure out a simple rule by using standards that are not present. This is not about the geometry of the backboard. If the ball is in the cylinder, there are things that cannot be done with the ball or the ring, net or ball under the right circumstances. I think you just need to review the rule and leave it at that. The backboard and the geometry of the backboard have nothing to do with the call of basket interference. And the box on the backboard is wider than the ring. Rule 4-6 covers this rule and you will not read anything about the backboard.

Peace

Sweet.
 

but what about the flange extending the ring out away from the board? that has to make that imaginary line closer to the center of the back board.

hrm.
 

Rut, if the ball was pinned by the defender on the gaudy red X in the image in the OP, can we agree that the defender may be touching the ball while the ball was in the imaginary cylinder with the basket as its base?

If the touching was not in the cylinder, where the ball touches the backboard might not be relevant.

As I said, I think you are taking a judgment call and trying to make a one size fits all application. If the ball is not in the cylinder, it is not BI. If you think it is in the cylinder (and certain things are present), then call a violation. You will find that at full speed you are not going to get a simple judgment based on a marking. If the ball hits the backboard does not mean it was touched at the very same spot.

Peace

I think that while it is possible theoretically to use the backboard markings to determine a violation, in reality one would need at least a slow motion replay for this to be useful. See it. Call it. Live with it. This is a call that is very often difficult to make with complete certainty.

i see where you are coming from.
 

I'm just intrigued by the geometry of it. Just to confirm, I'm talking about a pinned ball. Contacting the ball while it is in contact with the backboard.

I used to have a backboard and rim sitting in my garage. If i still had it I'd go roll a ball around on it and get some empirical knowledge. I am NOT willing to get a ladder out though.

That would be goaltending, not BI. As JRut has said, the backboard has nothing to do with BI.

"You Are Correct, Sir" (Ed McMahon)
 

This statement is 100% correct, but I believe that referee99 is trying to point out to us that the backboard limits the position of the ball, inside and outside, of the imaginary cylinder, when the ball is behind the basket. If the ball is on either side of the basket, to the left, or to the right, then it is possible for the ball to either be either inside the cylinder, or outside the cylinder. If the ball is in front of the basket, the it is possible for the ball, again, to either be inside the cylinder, or outside the cylinder. What, I think, referee99 is saying is that the backboard may be a limiting factor behind the basket, that is, if the ball is in contact with the backboard, and it's not too far to the left, or too far the right, of the basket, then that ball must, according to referee99, be inside the cylinder. The ball can't go farther back than the backboard, it's against the laws of physics. I'll let someone else work out the math, using the diameter of the ball, and the depth of the flange attached to the backboard. It's 19 degrees outside right now, and I refuse to go out onto my icy driveway, get up on a ladder, and check out referee99's theory on my basket and backboard.

Had a rec game last night...
 

On the side of the court were baskets at 8' height, so I got a chance to play with this.
When a mens basketball is placed so that the vertical center of the ball is aligned with the middle of the outer edge of the 'shooters rectangle' and the ball is touching the backboard, the ball is not touching the cylinder with the ring of the basket as its imaginary base. It is juuust outside of the cylinder.

Move it in 1" and it is touching that imaginary cylinder.

Call before you dig.
 

It's tough to argue with empirical data.

I still say you are making something that is simple into a much more complicated mess. If it works for you, I guess keep up the good work.

Peace